How many moles of ions are in each compound? a. 0.0200 g of AgNO 3 b. 0.100 mo

How many moles of ions are in each compound? a. 0.0200...

Key Concepts

Chemical Formula Interpretation

Interpreting a chemical formula involves recognizing the types and numbers of atoms or ions present in a compound. The subscripts in a chemical formula indicate the number of each type of ion or atom, and this information is key to calculating the total number of moles of ions produced upon dissociation.

Ion Dissociation

Ion dissociation is the process by which an ionic compound separates into its constituent ions when dissolved in a solvent such as water. Understanding the dissociation process is crucial for determining the number of moles of individual ions present in a solution, which depends on the formula and stoichiometry of the compound.

Molar Mass Calculation

Molar mass is the mass of one mole of a given substance, expressed in grams per mole (g/mol). It is calculated by summing the atomic masses of all atoms present in a compound’s chemical formula. This concept allows the conversion between the mass of a substance and the amount in moles, which is essential for quantitative chemical analysis.

Mole Concept

The mole is a fundamental unit in chemistry that represents a specific number of particles, usually atoms, molecules, or ions. It serves as a bridge between the microscopic scale of atoms and molecules and the macroscopic scale of grams and liters, enabling chemists to work with measurable amounts of substances.

Stoichiometry of Ionic Compounds

Stoichiometry involves the use of balanced chemical equations and mole ratios to determine the amounts of reactants and products in a chemical reaction. In the context of ionic compounds, it is used to calculate how many moles of each ion are produced from the dissociation of one mole of a compound, based on its chemical formula.

Transcript

00:01 All righty, so today we're looking for how many moles of ions are in each compound, and so we're going to kind of break this down into three steps that'll make it relatively easy for us to go through this problem.

00:11 And so step one is going to be to determine how many moles of each compound there are.

00:23 Step two is then going to be for us to find the ions.

00:32 And then step three is going to be to determine the molar ratios.

00:45 So let's go ahead and look at part a, which in part a we are looking for 0 .0200 grams of silver nitrate.

01:01 And so the first thing we need to do is to determine the moles of each compound.

01:07 And so since we're in grams, we're going to need to find the molecular weight of silver nitrate.

01:11 So for that, we're going to have the molecular weight of silver, which is 107 .87, the molecular weight of nitrogen, which is 14, and the molecular weight of oxygen, which is 16.

01:25 From there, we're now going to multiply out our oxygen is going to be times three because we have three oxygens in our compound where we have one silver and one nitrogen.

01:34 We can tell that by those subscripts there in the formula.

01:37 Formula, and then we are going to add all of this together, and that will give us a total of 169 .87 grams per mole of silver nitrate.

01:51 From here, we can use dimensional analysis to convert our grams into moles.

01:55 So we'll just have our 0 .0200 grams, and then from there, we're going to multiply that by one mole per 169 .87 grams.

02:08 And when you're doing your dimensional analysis, if you're ever confused about which one should go on top, just remember you always want your units to cancel so that you're left with the unit you want.

02:16 So here our grams are going to cancel and we'll be left with moles.

02:20 And so when we multiply that out, we get 0 .000118 moles, but that's kind of a clunky number to work with.

02:33 So we'll go ahead and convert that to 1 .18 times 10 to the negative fourth moles.

02:42 And so now we need to determine what the ions are.

02:45 And so here, looking at this, silver is a metal, so that's going to be one of our ions, where nitrate is a complex ion that you'll see pretty frequently in chemistry.

02:54 You've probably had to memorize those before.

02:57 And so we have our two ions.

02:59 They are silver and they are nitrate.

03:01 So now from here, we need to determine the molar ratios of these.

03:05 And so there is one nitrate and one silver for each silver nitrate.

03:10 So our molar ratios are going to be 1 to 1 to 1 to 1.

03:14 And so there is going to be one mole of silver and one mole of nitrate for every mole of silver nitrate.

03:20 Those are all going to be equal.

03:21 So then from there, this is going to be our answer.

03:24 They're going to be 1 .18 times 10 to the fourth moles of silver and 1 .18 times 10 to the negative fourth moles of nitrate.

03:32 So from here, we can continue on into part b.

03:37 And so part b is going to be 0 .100 moles of k2cro4.